Comparison of stress-activated models and linear spectral models for visco-elasticity

Author(s):  
Bertil Olofsson
Keyword(s):  
2021 ◽  
Vol 280 ◽  
pp. 109945
Author(s):  
Miguel Rene Mogollón ◽  
Carolina Contreras ◽  
Sergio Tonetto de Freitas ◽  
Juan Pablo Zoffoli

2010 ◽  
Vol 722 (1) ◽  
pp. 871-879 ◽  
Author(s):  
David S. Spiegel ◽  
Adam Burrows
Keyword(s):  

2006 ◽  
Vol 34 (1) ◽  
pp. 1-5 ◽  
Author(s):  
Mahender Singh ◽  
Ram Niwas ◽  
M. L. Khichar ◽  
Manoj K. Yadav

2019 ◽  
Vol 147 (2) ◽  
pp. 645-655 ◽  
Author(s):  
Matthew Chantry ◽  
Tobias Thornes ◽  
Tim Palmer ◽  
Peter Düben

Abstract Attempts to include the vast range of length scales and physical processes at play in Earth’s atmosphere push weather and climate forecasters to build and more efficiently utilize some of the most powerful computers in the world. One possible avenue for increased efficiency is in using less precise numerical representations of numbers. If computing resources saved can be reinvested in other ways (e.g., increased resolution or ensemble size) a reduction in precision can lead to an increase in forecast accuracy. Here we examine reduced numerical precision in the context of ECMWF’s Open Integrated Forecast System (OpenIFS) model. We posit that less numerical precision is required when solving the dynamical equations for shorter length scales while retaining accuracy of the simulation. Transformations into spectral space, as found in spectral models such as OpenIFS, enact a length scale decomposition of the prognostic fields. Utilizing this, we introduce a reduced-precision emulator into the spectral space calculations and optimize the precision necessary to achieve forecasts comparable with double and single precision. On weather forecasting time scales, larger length scales require higher numerical precision than smaller length scales. On decadal time scales, half precision is still sufficient precision for everything except the global mean quantities.


2012 ◽  
Vol 29 (9) ◽  
pp. 1329-1346 ◽  
Author(s):  
W. Erick Rogers ◽  
Alexander V. Babanin ◽  
David W. Wang

Abstract A new wind-input and wind-breaking dissipation for phase-averaged spectral models of wind-generated surface waves is presented. Both are based on recent field observations in Lake George, New South Wales, Australia, at moderate-to-strong wind-wave conditions. The respective parameterizations are built on quantitative measurements and incorporate new observed physical features, which until very recently were missing in source terms employed in operational models. Two novel features of the wind-input source function are those that account for the effects of full airflow separation (and therefore relative reduction of the input at strong wind forcing) and for nonlinear behavior of this term. The breaking term also incorporates two new features evident from observational studies; the dissipation consists of two parts—a strictly local dissipation term and a cumulative term—and there is a threshold for wave breaking, below which no breaking occurs. Four variants of the dissipation term are selected for evaluation, with minimal calibration to each. These four models are evaluated using simple calculations herein. Results are generally favorable. Evaluation for more complex situations will be addressed in a forthcoming paper.


Radiotekhnika ◽  
2019 ◽  
Vol 2 (197) ◽  
pp. 56-63
Author(s):  
А.В. Грицунов ◽  
И.Н. Бондаренко ◽  
А.В. Бородин ◽  
М.А. Копоть ◽  
Л.И. Свидерская

2009 ◽  
Vol 9 (4) ◽  
pp. 17465-17494
Author(s):  
D. B. Atkinson ◽  
P. Massoli ◽  
N. T. O'Neill ◽  
P. K. Quinn ◽  
S. Brooks ◽  
...  

Abstract. During the 2006 Texas Air Quality Study and Gulf of Mexico Atmospheric Composition and Climate Study (TexAQS-GoMACCS 2006), the optical, chemical and microphysical properties of atmospheric aerosols were measured on multiple mobile platforms and at ground based stations. In situ measurements of the aerosol light extinction coefficient (σep) were performed by two multi-wavelength cavity ring-down (CRD) instruments, one located on board the NOAA R/V Ronald H. Brown (RHB) and the other located at the University of Houston, Moody Tower (UHMT). An AERONET sunphotometer was also located at the UHMT to measure the columnar aerosol optical depth (AOD). The σep data were used to extract the extinction Ångström exponent (åep), a measure of the wavelength dependence of σep. There was general agreement between the åep (and to a lesser degree σep measurements by the two spatially separated CRD instruments during multi-day periods, suggesting a regional scale consistency of the sampled aerosols. Two spectral models are applied to the σep and AOD data to extract the fine mode fraction of extinction (η) and the fine mode effective radius (Reff f). These two parameters are robust measures of the fine mode contribution to total extinction and the fine mode size distribution respectively. The results of the analysis are compared to Reff f values extracted using AERONET V2 retrievals and calculated from in situ particle size measurements on the RHB and at UHMT. During a time period when fine mode aerosols dominated the extinction over a large area extending from Houston/Galveston Bay and out into the Gulf of Mexico, the various methods for obtaining Reff f agree qualitatively (showing the same temporal trend) and quantitatively (pooled standard deviation=28 nm).


2015 ◽  
Vol 30 (2) ◽  
pp. 535-537
Author(s):  
CAMILLA PACIFICI ◽  
ELISABETE DA CUNHA ◽  
STEPHANE CHARLOT ◽  
SUKYOUNG YI

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